Just received it in the mail today. Definitely OEM and adds a very minimal amount of bulk. The only thing it doesn't do is curve in around the bottom of the phone, making it look more uniform. My Amzer case also fits this perfectly and i'm sure all other do as well. Here's the link if interested.
http://www.ebay.com/itm/Genuine-Sam...Accessories&hash=item1c222d0cea#ht_4852wt_902
http://www.ebay.com/itm/Genuine-Sam...Accessories&hash=item1c222d0cea#ht_4852wt_902